Axially adjustable fuel burner for furnaces



May 28, 1957 E. D. PHILLIPS AXIALLY ADJUSTABLE FUEL BURNER FOR FURNACESFiled March 18, 1952 2 Sheets-Sheec 1 IIIiI III: I

FIG. 8

INVENTOR B EVERETT D. PHILLIPS ATTORNEY FIG.

y 1957 E. D. PHILLIPS 2,793,686

AXIALLY ADJUSTABLE FUEL BURNER FOR FURNACES Filed March 18, 1952 2Sheets-Sheet 2 FIG. 6

INVENTOR EVERETT. D. PHILLIPS B ATTORNEY United States Patent AXIALLYADJUSTABLE FUEL BURNER FOR FURNACES Everett D. Phillips, Danviile, Pa.;Rubye W. Phillips, executrix of said Everett 1). Phillips, deceasedApplication March 18, 1952, Serial No. 277,179 2 Claims. (Cl. 158--1.5)

This invention relates to furnace burners and more particularly to animproved design for a burner for industrial furnaces and boilers.

My invention is particularly designed to provide a burner capable ofoperation with oil, gas or powdered coal, depending upon the mosteconomical fuel available in the location where the burner is installed.The general structure of the burner remains the same irrespective of thefuel utilized, the burner itself being made adjustable to meet theparticular operating conditions necessary to obtain efficient combustionwith each of the fuels. Thus, my invention is universally applicable asa single design for a packaged unit, eliminating the costs entailed bythe necessity of constructing three different types of burners eachspecialized to the type of fuel with which it is to be used.

My invention is designed to provide a burner capable of complete andrapid adjustment at the time of installation to the particularcircumstances of the installation. Heretofore, conventional packagedburner designs provided a unit adapted to average operating conditions.These burners, however, were too inflexible and not adapted tomodification to meet the special operating conditions frequentlyencountered at the time of installation. In order to effect thenecessary modifications, these burners frequently had to besubstantially rebuilt in the field. This rebuilding often entailed theshortening or lengthening of whole sections of the burner, removal ofexcess parts or the incorporation of entirely different sub-as semblies.The result was a burner consisting of a patchwork of modified parts andonly partially adapted to the particular needs of the installationinvolved. Further, these field modifications, whether small or great,result in excessive installation costs as well as long and costly delayswhile the modifications are completed. These modifications necessitatean installation crew including not only an experienced combustionengineer but a crew of welders, sheet metal men and other mechanics inaddition to the normal installation crew necessary to initially mountthe burner on the furnace.

My invention entirely eliminates all of these installation difficultiesby providing a unit of such design that its various parts are renderedrapidly and easily adjustable to meet each and every operatingcondition. My invention is characterized by components which may beadjusted to meet operating conditions with a minimum of tools and, ifnecessary, by a single installation man, thus, eliminating the expenseof a large installation crew. Furthermore, the resulting burner does notconsist of a patchwork of modified parts and thus is capable of greaterefliciency in operation. Moreover, if so desired or required my burnercan be lifted bodily and in a single unit from its housing 7 by removingnuts from bolts 3 and lifting out, with replacement being made in thereverse order. Where a furnace using two or more burners are inoperation my burner can be removed and replaced without taking thefurnace out of service. By reason of the built-in adjustment featuresthe burner may be precisely adjusted the problems of combustionengineering upon reading the,

following specification and the accompanying drawings.

In the drawings:

Figure 1 is a central, sectional view of my invention showing the burnermounted to the front of a furnace.

Figure 2 is a sectional view taken along the plane II- II of Figure 1.

Figure 3 is a sectional view taken along the plane III-- III of Figurel.

Figure 4 is a sectional view of my invention looking toward the furnacebut showing only the relationship of the primary air inlets with respectto the remainder of the burner structure.

Figure 5 is a sectional view taken along the plane V-V of Figure 1.

Figure 6 is a sectional view taken along the plane VI-VI of Figure 1.

Figure 7 is an enlarged, fragmentary view of the means for regulatingthe primary and tertiary air flows.

Figure 8 is a view of the inner sliding secondary air control, rotatedabout its central axis from its position in Figure 1.

In executing the objects and purposes of my invention,

I have provided, adjacent the furnace wall, a secondary.

air chamber communicating with the throat of the furnace. Means areprovided for causing the air to spiral as it enters 'the throat of thefurnace. concentrically within this secondary air chamber is a tube forconducting primary air into the throat where it will become intermixedwith the secondary air for sustaining combustion. Means are providedwithin the primary air conduit for causing this air to spiral in thesame direction as the secondary air. A tertiary air inlet is providedfor introducing tertiary air to the primary air stream. The volume ofsecondary air entering the throat of the furnace is made adjustable aswell as the point at which the secondary air is actually discharged fromthe secondary air chamber into the furnace throat. Similarly, the pointof discharge of the primary air into the furnace throat is likewiseadjustable axially of the burner. Valve means are provided forcontrolling the admission of tertiary air into the primary air streamand for causing this air to spiral as it enters the primary air stream.Further adjustment means is provided to regulate the mixing orturbulence of the primary air within the burner whereby a thoroughdispersion of the fuel within the primary air is effected before it isdischarged into the throat of the furnace. concentrically of the entireburner structure is a pipe for introducing oil should this type of fuelbe utilized instead of a solid fuel carried by the primary air. Thequantity and point of introduction of secondary and primary air to theoil discharged from the pipe may be ad justed to assure maximumcombustion efficiency. The oil may also be used as a starter or igniterfor the burner when burning solid fuels.

In the following description the terms inwardly and outwardly arefrequently used and are to be taken to mean inwardly toward the furnaceand outwardly away therefrom. The terms externally and internally arealso frequently used and are to be taken to mean internally toward theaxial center of the burner and externally away therefrom.

a. Secondary air With specific reference to the drawings, the numeral 1indicates a furnace wall having a throat 2 therein. Attached to theoutward face of the furnace wall by the lug bolts 3 is an annular plate4 having an inwardly extending collar 5 seated in the throat 2. Attachedto the plate 4 is the cylindrical housing 7 for the secondary airchamber 8. It will be recognized that the housing 7 may be a square orpolyhedron but a circular shape is more efficient and satisfactory. Theouter end of the secondary air chamber 8 is closed by a removable cover9 bolted to the angle 10. The cover has a large, concentric, circularopening through which passes the guide collar 11. The guide collar 11extends a substantial. distance into the secondary air chamber and issupported by its flange 12 nesting against the outer surface of thecover 9. The flange 12 is rigidly secured to the cover 9by bolts,welding or other fastening means.

Air is admitted to the secondary air chamber 8 through the air intakeport 13 which enters the secondary air chamber 8 tangentially, whereby aclockwise rotation of the air is initiated in the chamber. Intake port13 is described as entering housing 7 tangentially, and housing '7 asbeing circular, also, the vanes in the various ports will be describedas being designed for production of clockwise rotation. This orientationof the ports has been used to simplify the description and is not to beconstrued as a limitation. Actually. intake port 13 can have the samewidth as that of housing 7 and housing 7 can be square or evenrectangular in shape. Further, both clockwise and counter-clockwiserotations will be used in diflerent burners serving the same furnace.Under certain circumstances, both clockwise and counterclockwiserotation may be used in the same burner.

Seated within the collar 5 is a conical ring 14 having a plurality ofradially inwardly directed vanes 15 (Figure 6). The conical shape of thering 14 is designed to urge the air inwardly. The vanes 15 are designedto urge the air to rotate clock-wise as it passes through them. The ring14 and the vanes 15 are movable axially of the collar 5 by means of therods 16. Each of the rods 16 passes through a boss 17 having a thumb.screw 18 for holding the rods in any particular position of adjustment(Figures 1 and 5 A pair of access ports 6 are provided in the cover 9(Figure 5). These ports 6 serve both as inspection windows and asopenings through which the burner may be lighted. The ports 6 are closedby covers having transparent windows to permit inspection. 7

b. Primary air Slida'bly seated within the guide collar 11 is the throatpiece 30. The throat piece 30 has an outer flange 21 connected to thecover 9 by three bolts 32 (Figures 1 and 4). By reason of the bolts 32,the throat piece 30 may be telescopically adjusted with respect to thecollar 11. The throat piece 30 has a concentric, conical passageway 33of decreasing diameter toward the furnace. The inward end of the throatpiece supports a tubular extension 34 extending inwardly into theopeningin the collar 5. The collar 5 and the extension 34 areconcentric.

Slida-bly mounted on the extension is the valve shaped piece 35 (Figures1 and 8). The valve piece includes a cylindrical slide 36 surroundingthe extension 34 and a pair of wings 37 to the ends of which areattached the adjustment rods 38. The rods 38 are spaced midway betweenthe rods 16 (Figure 5). The rods 38 extend outwardly through bosses 39mounted to the cover 9 (Figure 5). The rods are secured by thumb screws40 set in the bosses 39. On the inward end of the slide 36 is a conicalannulus 41 having its end of lesser diameter directed toward thefurnace. The annulus 41 is concentric with the slide 36 and is spacedtherefrom to create a tapered passageway therebetween. The slide 36 mayextend only partway into vanes 42 on annulus 41. The greater diameter ofthe annulus 41 is such that it may pass through the ring 14, the outerdiameter of the annulus substantially corresponding to the innerdiameter of the ring 14. The passageway within the annulus is equippedwith inclined vanes 42 designed to urge the air passing theretlirough torotate clockwise (Figure 6). The vanes 42 are attached to the annulusand to an extension of the slide for rigid support. The annulus 41itself is further anchored to the slide 36 by a pair of diametricallyplaced brackets 43 (Figure 8). The brackets 43 actually are speciallyshaped extensions of two or more of the vanes 42.

The outer end of the throat piece 30 is closed by a wide flange 44secured to an outwardly extending, concentric, tubular sleeve 45.Externally of the sleeve 45 are four, equally spaced, elongatedapertures 46 (Figure 4). These apertures communicate with the wide,outer end of the central passageway 33. To each of the apertures 46 isattached a tube 47. The tubes 47 extend outwardly from the flange 44tracing a counter-clockwise, spiral path. As they extend outwardly,their shape changes from that of the elongated apertures 46 to that of acircle. During this transition in shape, the internal, crosssectionalarea of the tubes remains the same, only the shape of the internalpassageway changes. These tubes introduce the primary air to the burnerand their outward, counterclockwise, spiral path is designed to causethe air to circulate clockwise as it enters the passageway 33.

The primary air is again caused to spiral by the vanes 48 on the inwardend of the hereinafter described central tube 80.

c. Tertiary air Telescopically received through the sleeve 45 is thecylindrical, tertiary air duct 60. The duct 60 is provided with an inletport 61 adjacent its outward end. The duct is of such length that itprojects through the sleeve 45 into the passageway 33. Its inward end isbeveled at 62 to permit it to form a seal against the converging,internal walls of the throat piece 30. The duct 60 is adjustable axiallyof the burner, its position being controlled by the bolts 63 (Figures 1and 3). The bolts 63, at their outer ends engage the lugs 64 extendingradially from the duct and, at their inner ends, engage the radiallyextending flange 65 on the outward end of the sleeve 45. An annularbuffer ring 65a rests above but is separate from flange 65 and isslidably and axially mounted in relation to flange 65, bolts 63, andduct 60. The annular buffer ring 654 has an outside diameter equal tothe outside diameter of flange 65.' The outward end of the duct 60 isclosed by the annular cap 66 and a sealing ring 67. Slidably mountedthrough the cap, 66 are a pair of con trol rods 68 and 69. The controlrod 68 extends a substantial distance into the duct 60 and on its endmounts a valve ring 70. The valve ring has a large, central openingentering, at its inward end, into the conical valve seat 71. The damperring 70 is slidable axially of the duct 60, its position beingcontrollable by means of the control rod 68. Inwardly of the damper ring70 is the annular block 72. The annular block 72 is slidably mounted onthe hereinafter described central tube 80. The block 72 is adjustableaxially of the duct 60, its position being controllable by means of thecontrol rod 69. About the inward end of the block 72 are arranged aplurality of equally spaced, inclined fins 73 (Figure 7) designed toimpart clockwise rotation to the tertiary air before this air isdischarged from the duct 60. The position of the control rod 68 issecured by the set screw 74 in the boss 75. The position of the controlrod 69 is secured by theset screw 76 in the boss 77.

d. Igniting equipment wardly beyondthe cap 66 and at its end has aremovablecap 8.1, secured tothecentral tube 80 by the set screw 82.Extending co-axially, through the central tube 80 is a greases pipe 83having a nozzle 84 on its inward end. The nozzle is supported againstradial movement by the spacer 85. The pipe 83, at its outward end, isprovided with a valve 86. A support conduit 87 for the pipe 83 parallelsthe pipe 83 and passes through the arm 88 of the cap 81. The conduit 87is locked to the arm 88 by the screw 89. Normally, the liquid fuelsupplied by the pipe 83 is atomized by means of steam. Both the oil andthe steam are introduced to the pipe 83 at its outward end throughflexible hoses (not shown). The valves 86 and 90 provide individualcontrol for the steam and the fuel.

OPERATION The fundamental principles of operation of my improved burnerare basically the same as those of existing conventional burners, theprimary differences lying in the operation of the burner at the time itis installed and in the manner in which the operation of the burner iscarried out when the burner is complete and functioning.

At the time the burner is installed, the primary consider ation is theadjustment of the burner to meet the operating conditions of theparticular installation. It is at this point that the structure of myburner appears as a most important advancement since it permitspractically unlimited adjustment. Preferably, the burner is partiallydisassembled at the time of installation by removing all of thatstructure extending outwardly from the secondary air chamber 8 exceptthe throat piece 30. In this stripped down condition, the secondary airchamber may be mounted to the furnace wall by means of the lugs 3passing through the annular plate 4. With the secondary air chamber 8 inplace, the remainder of the structure may be attached by bolting thesleeve 45 to the throat piece 30. After this has been done, thenecessary attachments may be made to the primary, secondary and tertiaryair leads and the pipe 87 may be connected to a suitable source ofliquid or gaseous fuel. The burner can be installed completelyassembled, if the circumstances warrant it.

At this point the burner is installed but the important process ofadjusting the burner to provide satisfactory combustion must now bemade. Heretofore, at this point, great time was lost and extendeddifficulties were encountered because the burners were incapable ofmaking the necessary adjustments to meet the particular combustionrequirements of each individual installation.

To provide satisfactory combustion, it is essential not only that aproper air and fuel ratio be obtained but it is essential that the fuelbe thoroughly intermixed with the air to produce complete combustion. Itis also necessary that the shape and velocity of the fuel-air stream beregulated to produce a flame of satisfactory shape. Further, it isessential that the point of combustion, that is, the point of ignitionof the fuel-air mixture be properly located within the burner ring orthroat of the furnace. If this point of ignition of the fuel-air mixtureis located too deeply within the furnace, it may result in injury to thewalls of the furnace as well as poor combustion of the fuel. If theflame is located too close to the burner ring, again poor combustion.This same flame Will also cause rapid deterioration of the burner ring,necessitating frequent replacement. The shape of the flame is dependentin part upon the type of path the secondary air is travelling as itenters the burner ring and in part upon the point with respect to theburner ring the primary air carrying the fuel is introduced to thesecondary air. The position of the flame with respect to the burner ringis determined largely by the point of introduction of the primary air tothe secondary air.

When pulverized, solid fuels are used, the primary air functions only asa fuel carrier. Only sufiicient primary air is introduced to the burneras is necessary to etnciently transport the fuel from the pulverizer tothe burner. Excessive air is not utilized in order to maintain anonexplosive fuel-air ratio. Where the proportion of air to fuel is lowthe mixture. is too rich to ignite or if ignited, to sustain combustion.Since fuels may vary it becomes necessary to adjust the quantity ofprimary air necessary to transport the fuel. This is particularly truewhere the fuel may vary from dry to wet. When the fuel is wet,additional air is necessary to transport the heavy fuel and, therefore agreater proportion of the combustion air is introduced through theprimary air stream. Where, however, the fuel is very dry, the proportionof air entering by means of the primary air stream may be quite small.in fact, it may be so small that insufficient air is provided by theprimary air stream together with the secondary air stream to insureideal combustion conditions. When this is the case, the provision for atertiary air stream becomes important because this permits introductionto the primary air stream, at the burner, sufiicient additional air tomake up the difference and thus at all times insure .an ideal combustionmixture.

Considering first the normal operating conditions wherein only primaryand secondary air is used, by means of the rod 68 the damper ring 70 ismoved inwardly until it tightly engages the annular block 72. This shutsoff the tertiary air supply. The primary air is introduced through thepipes 47.

It is an important feature of my burner that the primary air isintroduced axially of the burner rather than tangentially. Heretofore,it has been common practice to introduce this fuel-air mixturetangentially, and perpendicularly to the axis of the burner. Thisresults in appreciable velocity loss of the primary air wherebyquantities of the fuel drop out and accumulate in the burner. Not onlydoes this result in improper combustion and a general disruption of theefliciency of the furnace but it can result in the accumulation of fuelswhere they may ignite. These fuel accumulations sometimes produce firesand periodically cause serious explosions. By introducing the solid fuelaxially of the burner there is no reduction in the velocity of theprimary air and thus the fuel is not permitted to drop out ofsuspension. Therefore, all of the fuel is carried into the combustionchamber of the furnace and no dangerous accumulations occur within theburner itself.

By reason of the spiraling of the pipes 47, the primary air, as it isintroduced to the burner, is given an initial clockwise rotation. Thepipes 47 discharge the primary air with its fuel into the outer part ofthe throat piece 3t). This mixture, rotating in a clockwise direction,then passes through the restricted passageway 33 between the inclinedsides of the throat piece 30 and the end of the tertiary airduct 60. Itis important that sufficient turbulence be created in the primary airstream at this point to assure a thorough mixing of the fuel throughoutall portions of the primary air. To effect this mixing, the passageway33 is adjusted to a size such that the particular volume of primary airpassing through this passageway will be caused to accelerate as itpasses the end of the tertiary air duct 60 and then enter a turbulentair pattern in the inward portion. of the throat piece 39. This is doneby axially adjusting the tertiary air duct 60 by means of the bolts 63.Thus, not only may the desired turbulence be created to effect mixing atthe time the burner is installed, but this passageway 33 may be adjustedfrom time to time during the operation of the burner to accommodatevarying volumes of primary air necessitated by the condition of the fuelbeing utilized. The movement of the tertiary air duct 60 axially of theburner does not affect the closure of the damper ring 70 since thisentire structure moves bodily with it.

After the primary air leaves the throat piece 30 it travels through theextension 34 and adjacent the inward end of the extension 34 is againforced into a clockwise spiral path by the vanes 48. The exact point atwhich the primary air is acted upon by the vanes 48 may be determined byaxial adjustment of the central tube 80.

The position at which the primary air is discharged 'creating anelongated narrow flame.

into the secondary air stream with respect to the burner ring 2 is madeadjustable. By means of the bolts 32, the throat piece 39 may be movedaxially of the secondary housing- 7. The movement of the throat piece 3%moves with it the entire structure outwardly of the throat piece and allof the structure passing through the throat piece. Thus, the entirestructure relating to the primary and tertiary airs may be movedinwardly or outwardly as required. The exact position at whichsatisfactory cornbustion will be produced is dependent upon a number offactors. One of these factors is the proportion of combustion airentering through the primary air lead with respect to the proportion ofthe combustion air entering through thesecondary air lead. It willdepend in part upon the velocity of the air as it enters the burner aswell as the shape and size of the burner ring 2 and the size of thefurnace with which the burner is to be used. The quality and type offuel employed will also have an appreciable influence upon this matter.It is thus seen that it is essential to make the burner adjustable tomeet each of these factors since each of them may vary from oneinstallation to another and from time to time during the operation ofthe furnace.

The secondary air enters through the conduit 13. The tangentialarrangement of the conduit 13 with respect to the secondary air chamber8, causes the air to circulate within the secondary air chamber 8. Sincethe secondary air is forced in under pressure, it is forced to escapethrough the conical ring 14. The conical ring restricts the passage ofthe air thereby increasing its velocity and at the same time bringing itinto contact with the vanes 15. The already circling air is forced intoa precise spiral pattern by the "anes as it enters the burner ring Sincethe point at which the secondary air is released from the conical ring14, into the burner ring 2 is important in determining the length andshape of the flame produced in the furnace, the conical ring 14 is madeadjustable axially of the burner. By adjustment of this conical ring,the flame may be extended further into the furnace or it may bewithdrawn closer to the burner ring. The axial movement of the conicalring 1 3 also permits the ring to be moved in conjunction with theprimary air lead whereby the two may be maintained in a particularrelationship while, both are moved inwardly or outwardly with respect tothe combustion chamber of the furnace.

The quantity of secondary air passing through the conical ring 14 aswell as the shape of the stream of air escaping into the burner ring 2may be controlled by movement of the annulus 43.. The further theannulus 41 is moved into the conical ring 14 the greater the restriction of the amount of air which may pass between the annulus andthe conical ring 1.4. When the annulus 41 is moved to its maximum inwardposition, it serves as a damper substantially stopping all air whichwould otherwise pass through the conical ring 14 into the burner ring 2.Under these circumstances, some air will pass through the passage withinthe annulus 41 and in turn will be caused to spiral by the vanes 42 inthis passage. The use of the annulus in its most inward position willresult in a narrow ring of air entering the burner ring 2, which ringvof air will be spiraling at a relatively high velocity due to therestriction of the passageway through the annulus. When the annulus ismoved to a position where it does not completely block the passage ofair through the conical ring 14 but merely severely restricts it, theresulting shape of the air stream will be a cone converging as it.passes through the burner ring 2. Such a cone will impinge upon theprimary air thereby This is desirable in certain installations.

Where the fuel is particularly dry or where a su stantial portion of thekinetic energy of the primary air stream is absorbed in the pulverizer,it may become necessary to supplement the primary air with tertiary airin order to provide suflicicnt air for efficient combustion. Tointroduce tertiary air, the damper ring is moved outwardly to permit thedesired quantity of tertiary air to pass through the tertiary air tube60. Before the tertiary air is introduced to the primary air in thethroat piece 3i) it is caused to enter a spiral path by means of theinclined fins. 73. The precise shape of this spiral as it enters theprimary air stream may be controlled by axial manipulation of theannular block 72 upon which the fins 73 are mounted. At the same time,the correct point for introduction of the tertiary air to the primaryair stream may be determined by axial movement of the tertiary air duct60.

The pipe 83 is used to introduce a liquid fuel primarily for lightingthe burner. When the burner is to be lighted, one of the access ports. 6is opened to permit an igniting means to be introduced to the stream ofliquid fuel, such as oil, being sprayed from the nozzle 84. In this caseonly secondary air is used. Once the oil stream has been ignited and theburner ring 2 has been sufficiently heated, primary air is introduced.When a self-supporting flame has been established dependent upon thesolid fuel, the oil is shut off by means of the valve 86.

It will be recognized that my burner provides a unit which is not onlysimple to install and adjust for optimum combustion but a unit which maybe readily and easily cleaned and repaired. Any part of the unit may bereached without extensive disassembly. The burner may be taken apartsection by section or it may be taken apart by removal of a few largesub-assemblies whereby the particular part to be cleaned or repaired isquickly made accessible. When desired the entire burner may be removedas a unit. At the same time, my burner provides a compact unit designedfor burning fuels under a forced draft, in which the quantum of air tofuel may be quickly, precisely and easily regulated and in which theintroduction of air into the furnace is confined to those streamssubject to complete regulation. The burner does not admit of numerousair leaks which frequently cause inefficient combustion and lack ofcombustion control in conventional burners. It is further seen that myburner may be precisely constructed and this precision can be carriedover into the burner after it has been installed because it isunnecessary to make any structural changes in the burner since alladjustments necessary for efficient operation are permitted by theoriginal, factory built structure.

When the furnace is to be used to burn liquid fuels, the liquid fuel maybe introduced through the burner as it is initially constructed forsolid fuels by use of the pipe 83 and the nozzle 84. When a liquid fuelis thus used the tertiary air duct 60 may be moved inwardly until a sealis ellected between the chamfercd inward edge as of this duct and thewalls of the central passageway of the throat piece 30. At the sametime, the damper ring 7% is moved inwardly to effectively shut off thetertiary air. Valves in the air supply system for the burner andexternal of the burner, adapted for rapid operation, may be used forshutting off the primary and tertiary air in lieu of disturbing theadjustments for solid fuels. The liquid fuel is then burned with onlythe secondary air stream operating. The inward movement of the tertiaryair duct 66 will cause the nozzle 84 to move inwardly with respect tothe burner ring 2. This may be compensated by moving the central tubetogether with the pipe 83 outwardly with respect to this tube. Therequired adjustments for proper combustion may be effected bymanipulation of the conical ring 14 and of the annulus 41.

When gaseous fuels are burned, it is possible to use my burner withoutmodification of the structure. The gaseous fuel is introduced throughthe same tubes. 47 as are used for a pulverized, solid fuel. In thiscase, the tertiary air is shut off and the gaseous fuel caused tospiral. and enter the burner ring where the combustion mixture will beformed to fire the furnace at the desired point in the burner ring.Since all of the various parts of my furnace are adjustable, the exactpoint of ignition of this mixture may be closely regulated to positionit correctly with respect to the burner ring.

Numerous modifications of my invention may be made without departingfrom the principle thereof.

I claim:

1. In a burner assembly, the combination including: a housing havingtherein a secondary air chamber; a primary air conduit concentricallymounted to said secondary air chamber, a portion of said primary airconduit extending through said secondary air chamber; a tertiary airconduit concentrically mounted to said primary air conduit and adaptedto discharge into said primary air conduit; said primary air conduitbeing axially adjustable with respect to said housing; a conical ringmounted in the discharge end of said housing for movement axially ofsaid housing; a plurality of inclined vanes mounted within said conicalring; a, conical annulus slidably mounted on said primary air conduitand movable into said conical ring; the greater external diameter ofsaid annulus being substantially equal to the lesser internal diameterof said conical ring; an air passage between said annulus and saidprimary air conduit; a plurality of inclined vanes mounted in said airpassage.

2. In a burner assembly, the combination including: a housing havingtherein a secondary air chamber; a primary air conduit concentricallymounted to said secondary air chamber, a portion of said primary airconduit extending through said secondary air chamber; a tertiary airconduit concentrically mounted to said primary air conduit and adaptedto discharge into said primary air conduit; said tertiary air conduitbeing axially adjustable with respect to said primary air conduit; saidprimary air conduit being axially adjustable with respect to saidhousing; a conical ring mounted in the discharge end of said housing formovement axially of said housing; a plurality of inclined vanes mountedwithin said conical ring; a conical annulus slidably mounted on saidprimary air conduit and movable into said conical ring; the greaterexternal diameter of said annulus being substantially equal to thelesser internal diameter of said conical ring; an air passage betweensaid annulus and said primary air conduit; a plurality of inclined vanesmounted in said air passage; a plurality of inclined vanes mounted insaid tertiary air conduit for reciprocating movement axially of saidtertiary air conduit; a plurality of inclined vanes mounted in saidprimary air conduit adjacent the discharge end thereof for reciprocatingmovement axially of said primary air conduit.

References Cited in the file of this patent UNITED STATES PATENTS1,136,849 Tucker Apr. 20, 1915 1,870,013 Keenan Aug. 2, 1932 1,950,980Frisch Mar. 13, 1934 2,055,366 Schrader Sept. 22, 1936 2,181,527 VollmerNov. 28, 1939 2,275,394 Hardgrove Mar. 3, 1942 2,335,188 Kennedy Nov.23, 1943 FOREIGN PATENTS 469,254 France May 15, 1914 323,578 GreatBritain June 13, 1929 363,396 Great Britain Dec. 11, 1931

